Transformer Simulation in LTSpice

[jalbers@bsu.edu]

I have just started using LTSpice . I am slowly learning how to use
the simulator. I thought that I would try to simulate a 1:3 step up
transformer.

https://ilocker.bsu.edu/users/jalbers/WORLD_SHARED/Electronics/Transformer1.asc

I thought that I followed the directions that I found correctly:

Draw 2 inductors.
Add SPICE directive: K1 L1 L2 1 .
Set L1, L2 inductance ratio.

When I do a simulation, the voltage across the secondary is always
much lower than the voltage at the primary even if I play with the
values for L1 L2 or R2 .

I am aware of the LTSpice user group on Yahoo, but think that this
question would be a nuisance to that group.

Any help would be greatly appreciated. Thanks

 

[Paul E. Schoen]

<jalbers@bsu.edu> wrote in message
news:826ed892-5ed0-432c-b1d7-437ef9bcae65@a12g2000yqm.googlegroups.com...

I have just started using LTSpice . I am slowly learning how to use
the simulator. I thought that I would try to simulate a 1:3 step up
transformer.

https://ilocker.bsu.edu/users/jalbers/WORLD_SHARED/Electronics/Transformer1.asc

I thought that I followed the directions that I found correctly:

Draw 2 inductors.
Add SPICE directive: K1 L1 L2 1 .
Set L1, L2 inductance ratio.

When I do a simulation, the voltage across the secondary is always
much lower than the voltage at the primary even if I play with the
values for L1 L2 or R2 .

I am aware of the LTSpice user group on Yahoo, but think that this
question would be a nuisance to that group.

Any help would be greatly appreciated. Thanks

You should use mH rather than uH for 60 Hz. And the voltage ratio is the
square root of the inductances.

Paul

Try this:


Version 4
SHEET 1 880 680
WIRE -16 80 -144 80
WIRE 192 80 64 80
WIRE 528 80 288 80
WIRE 528 96 528 80
WIRE -144 128 -144 80
WIRE 192 128 192 80
WIRE 288 128 288 80
WIRE -144 256 -144 208
WIRE 192 256 192 208
WIRE 192 256 -144 256
WIRE 288 256 288 208
WIRE 528 256 528 176
WIRE 528 256 288 256
FLAG -144 256 0
FLAG 288 256 0
SYMBOL ind2 176 112 R0
SYMATTR InstName L1
SYMATTR Value 100m
SYMATTR Type ind
SYMBOL ind2 304 112 M0
WINDOW 0 -5 39 Right 0
WINDOW 3 -57 78 Left 0
SYMATTR InstName L2
SYMATTR Value 900m
SYMATTR Type ind
SYMBOL voltage -144 112 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value SINE(0 50 60)
SYMBOL res 80 64 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R1
SYMATTR Value 2
SYMBOL res 512 80 R0
SYMATTR InstName R2
SYMATTR Value 10MEG
TEXT 304 112 Left 0 !K1 L1 L2 1
TEXT -176 280 Left 0 !.tran 5

 

[Andrew Holme]

<jalbers@bsu.edu> wrote in message
news:826ed892-5ed0-432c-b1d7-437ef9bcae65@a12g2000yqm.googlegroups.com...

I have just started using LTSpice . I am slowly learning how to use
the simulator. I thought that I would try to simulate a 1:3 step up
transformer.

https://ilocker.bsu.edu/users/jalbers/WORLD_SHARED/Electronics/Transformer1.asc

I thought that I followed the directions that I found correctly:

Draw 2 inductors.
Add SPICE directive: K1 L1 L2 1 .
Set L1, L2 inductance ratio.

When I do a simulation, the voltage across the secondary is always
much lower than the voltage at the primary even if I play with the
values for L1 L2 or R2 .

V1 is not the voltage on the primary. Most of V1 is dropped across R1. You
only have about 0.9V peak across L1 giving 1.6V peak across L2.

I won't repeat the valid points already made by another poster.

 

[Phil Allison]

<jalbers@bsu.edu>

I have just started using LTSpice . I am slowly learning how to use
the simulator. I thought that I would try to simulate a 1:3 step up
transformer.

** Lemme give ya some good advice.

Circuit simulators are a real lot like dogs ......

and the first rule of dog training is that the trainer has to be smarter
than the dog.



....... Phil